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Conclusions Tracking spring runoff hydrographs will assist future management decisions regarding recovery of endangered fish species in the Green River. The data can be used to support recommendations involving the flow hydrograph variables of timing, frequency and duration. The variability in the Green River seasonal hydrograph are primarily a function the Yampa River flows. The Green River hydrographs shown in Figures 3a through 3d reveal several important facets of the spring runoff in the basin. Downstream of the Jensen gage, the Green River is a gaining river. The travel time from Jensen to Canyonlands for flows in the ranges from 12,000 to 18,000 cfs is approximately 85 hours, with a mean velocity of 3.5 fps. For flows from 5,000 to 12,000 cfs, the travel time is approximately 100 hours with a mean velocity of 3.0 fps. The sharp peak discharge at Jensen flattens and increases in duration with the inflows from the White and Duchense Rivers, both of which are controlled by water projects. The rating curves established for the various level loggers-are very good because the channel morphology is relatively stable over the range of discharges measured. The level logger data was recorded in either 15 minute, 30 minute or one hour intervals. Both stage and temperature data is recorded by the level loggers. A Fortran program -called Logger was created to reduce the incremental data to average daily discharges and temperatures. The data, results and program is available from U.S. Fish and Wildlife Service, Engineering Division in Denver, Colorado. In Figure 3a, the Mitton Parlc and Ouray Wildlife Refuge recorder partial hydrograph data is shown. These recorders were removed to avoid inundation. In addition, the Ouray Wildlife Refilge recorded performed poorly as shown in Figure 3b. It is recommended that these recorders be replaced by level loggers next year. The USGS Green River gage appears to be subject to rating curve shifts related to sediment ' movement in the alluvial channel. This phenomena was also noted in 1995 channel monitoring report. Three discharge measurements were made during the 1996 high flow season at the Green River gage by the USGS. These discharge measurements were made on Apri125, May 23 and June ' 2S and the applied shift was 2.4, -0.23 and 1.4 respectively. As the channel bed elevation increases with sediment storage or decreases with bed scour, the rating curve is affected requiring additional discharge measurements to recalibrate the gage. 1t is~recommended that more frequent discharge ' measurements should be performed by the USGS during the higher (lows of the spring runoff hydrograph to improve the resolution of the discharge estimates during stage shifts. Reviewing Figure 3c indicates a peak discharge at the Green River gage of 1,000 cfs to 2,500 cfs in excess of ' the peak flows at Desolation and Canyonlands. On the recessional limb of the hydrograph, the discharge at Green River is consistently less than the discharge at both the Desolation and Canyonlands level loggers and a 1,000 cfs drop was observed in the Green River data over a three day period from June 12 to June 14 that is not noted in any of the other gages. The effects of channel storage and floodwave attenuation is apparent in Figure 3a. On the rising limb of the spring runoff hydrograph, the discharge downstream of the White River confluence is greater than the discharge at both the Green River USGS gage and the Canyonlands level logger. 1 l5